Molding press



Oct. 12, 1937. H. D. THWEIATT ET AL MOLDING PRESS Filed Nov. 9, 1936 6 SheetsSheet l H. D. THWEATT ET An." 2,095,299

MOLDING PRESS s sheets-sheet 2 Filed Nov. 9 1936 g 2 a l 120427250715 Oct. 12, 1937. H. D. THWEATT El AL MOLDING PRESS 6 Sheets-Sheet .3

Filed Nov. 9, 1936 Oct. 12, 1937. H. D.THWEATT ET AL MOLDING PRESS Filed N09,. 9, 1936 6 Sheets-Sheet 5 Patented Oct. 12, 1937 'Y-UNI'TED, STAT-E MOLDING PRESS Hardin D. Thweatt and Otto Hoffmann, Buffalo,

N. Y., assignors to poration, Kenmore, N. York Lake Erie Engineering Cor- Y., a corporation of New Application November 9, 1936, Serial No. 109,868

14 Claims.

This invention relates to a molding press which is" more particularly designed for subjecting. articles ofplasticmaterial while in molds to hydraulic pressure for the purpose of shaping this material in accordance with the molds and comsame can be loaded and unloaded with greater facility and convenience; also to insure greater accuracy in the operation of the press so as to obtain uniform. products; and also to improve the construction of the operating mechanism in several details as will be hereinafter set forth.

In the accompanying drawings;

Fig. 1 is a front elevation of a molding press embodyingthese improvements and showing the parts. in the position which they occupy when the molds have been. moved into a position in which they are parallel and opposed but separated preparatory to effecting the final. closing squeeze on the plastic articles in the molds.

Fig. 2 is a side elevation of the same.

Fig. 3 is a vertical longitudinal section of the press, on an enlarged scale, taken on line 3-3, Fig. 1, and showing the parts in the position in which the molds diverge forwardly for discharging a charge of pressed articles and receiving a charge of unpressed material.

Fig. l is a fragmentary rear elevation of one of the control devices for the upper mold and associated parts.

Fig. 5 is a fragmentary vertical section on an enlarged scale, takenon line 5-5, Fig. 15, and showing the means for cushioning the drop of the stripper actuating ring.

Fig. 6 Ba vertical longitudinalsection, on an enlarged scale, taken on line 5-45, Fig. 1.

Fig. '7 is a fragmentary vertical section, on an enlarged scale, taken on line Fig. 6.

Fig. 8 is a horizontal section, on an enlarged scale, taken on line 8-8, Fig. 6.

Fig. 9 is a vertical longitudinal section taken on line 9-9, Fig. 8.

Fig. 10 is a fragmentary taken on line Iii-4D, Fig. 9.

Figs. 11 and 12 are fragmentary vertical sections, on an enlarged scale, taken on the correspondingly numbered lines in Fig. 6.

Fig. 13 is a fragmentary vertical cross section 55 taken on line l3--|3, Fig. 10,

horizontal section Fig. 14 is a fragmentary horizontal section taken on line I l-l4, Fig. 9.

Fig. 15 is a horizontal section, scale, taken on line l5-l5, Fig. 6.

Fig. 16 is a. fragmentary vertical section, taken on line l6-l 6,Fig. 15.,

Fig. 1'7 is a view similar to Fig. 16 the parts in a different position.

Fig. 18 is a vertical section, on an enlarged scale, taken on line l8'-|8, Fig. 2.

. Fig. 19 is a view similar to Fig. 18, but showing the parts in a different position.

Figs. 20 and 21 are fragmentary horizontal sections taken on lines 20-40, and 2|--2I,, respectively in Fig. 18. a

Fig. 22 is a fragmentary-vertical section similar to Fig. 9, but showing the parts in a different position.

. In the following description similar characters of reference indicate like parts in the several figures of the drawings.

The main frame or stationary part of the press which supports the movable or working parts of the same may be variously constructed, but as shown in the drawings, the same comprises a lower base 30, an upper head 3|, and two upright side plates 32 connected attheir upper and lower ends with opposite sides,yrespectively, of the base and head for the purpose of tying the same together rigidly. 3

Within the space between the base, head and side plates of the frameare arranged the upper and lower molds 33, 34 which preferably have the form of plates and which are provided on their respective opposing faces with complementary mold cavities 35, 36 which correspond to the shape of the. articles to be molded and pressed into the desired form by the press. These molds are movably mounted on the frame so the same may be projected forwardly from the frame into a position in which the molds diverge forwardly in a vertical plane, as shown in Fig. 3, and thus render the mold cavities conveniently and easily accessible to the operator for loading unpressed plastic or other material into the mold cavities prepara tory to pressing the same and also permitting the articles after the same have been finished by the co-operating pressure of the molds to be removed therefrom in like manner. After the molds have been loaded the same are retracted rearwardly. so that the same are arranged between the base and head of the frame and assume a position in which the faces of two molds are horizontal and. parallel with each other, as shown in Figs. 1, 2 and 6. Subsequently the upper mold remains at on an enlarged but showin rest and the lower mold moves upwardly toward the upper mold for the purpose of pressing between their respective mold cavities the material therein and forming the same into the desired shape. After this pressing operation has been completed, the lower mold first descends while the upper mold is at rest so that the molds separate from one another while their faces are parallel, as shown in Figs. 1, 2 and 6, at which time the finished articles are withdrawn from the upper mold and remain in the lower mold, and then both the upper and lower molds are moved forwardly from the frame so that the upper mold inclines upwardly and the lower mold inclines downwardly, as shown in Fig. 3, thereby providing a wide opening space between the molds which enables the pressed articles to be readily removed from the lower mold cavities and to be replaced by another batch of unpressed material. 7

The means for supporting and guiding the upper mold during these movements are constructed as follows:--- 7 The numeral 31 represents an upper bolster which in its operative position is arranged horizontally within the frame and bears with its upper side against the underside of the frame head 3|. Below this upper bolster is arranged an upper bed or intermediate 'filler plate 38 which may be detachably secured thereto in any suitable manner, for example by bolts 39 connecting brackets 40, 4| arranged on the corresponding front and rear ends of the upper bolster and bed plate, as shown in Figs. 1 and 3. The upper mold 33 en gages the underside of the upper bed plate and is detachably connected therewith, preferably by bolts 42 passing through lugs 43, 44 arranged respectively at the front and rear ends of the upper bed plate and upper mold, as shown in Figs. 1 and 6. This mold carrying unit comprising the upper mold, upper bolster and upper bed plate is guided on the main frame to secure the abovedescribed movement of the upper mold by'means of front and rear rollers 45, 46 pivotally mounted on the front and rear parts of opposite sides of the upper bolster and running on front and rear tracks or rails 41, 48 arranged adjacent to these rollers. Each of the front tracks or rails 41 has a downwardly curved front upper surface 49 and a horizontal rear upper surface 50 and has its rear part secured to the inner side of the adjacent frame plate 32 and its front part secured to a bracket 5! projecting forwardly from the respective frame side plate, as shown in Figs. 1, 3 and 6. Each of the rear tracks 48 is provided with a downwardly curved front upper surface 52 and a horizontal rear upper surface 53 and is secured to the inner side of the respective frame side plate 32, as shown in Fig. 3.

While the upper mold carrying unit is in its rearmost position the front and rear rollers 45, 46 engage with the horizontal rear surfaces 5!], 53 of the tracks 41, 48 and hold this unit in a horizontal position and with the upper bolster in engagement with the head of the frame so that the latter forms a solid abutment for the upper mold to resist the upward thrust which is exerted against the same during the operation of pressing the articles being molded between the lower and upper molds. Upon moving the upper mold carrying unit forwardly the front rollers 45 first run off the horizontal'surfaces 50 of the front track 41, thence slightly downward on the lower rear parts of the curved surfaces 49 and then upwardly on the elevated front parts of these'curved surfaces, whereby the front part of the upper mold carrying unit is first moved downwardly away from the abutment formed by the upper frame head and then the front part of this unit is tipped or tilted upwardly at an angle. At the same time the rear rollers 46 first run forwardly off the horizontal track surfaces 53, thence downwardly on the rear part of the curved surfaces 52 of the rear'tracks 48 and thence upwardly on the front parts of the curved surface 52, whereby the rear end of the mold carrying unit is moved away from the underside of the frame head and tipped or tilted downwardly relative thereto at the same time that the front part of the mold carrying unit is tilted upwardly relative to the frame head. During the rearward movement of the mold carrying unit the procedure is obviously reverse of that described with reference to its forward movement.

The means for supporting and guiding the lower mold during its longitiudinal or fore and aft movement are constructed as follows:-

The numeral 54 represents a lower bolster which is movable forwardly and backwardly from between the base and head of the frame and also movable vertically toward and from this head. Upon this lower bolster is mounted a lower or intermediate filler plate 29 which is detachably secured thereto by bolts 55 passing through brackets 56, 5'! arranged respectively on the front and rear parts of the lower bed plate and lower bolster, as shown in Figs. 1, 3 and 6. The lower mold is detachably secured to the top of the lower bed plate by bolts 53 passing through companion lugs 59, 50 on the front and rear ends of the lower mold and lower carrying plate, as shown in Figs.

1, 3 and 6. The lower mold, lower bed plate and lower bolster together form a lower mold carrying unitwhich is movable into and out of a position below the upper mold unit and when this lower unit is arranged in its rearmost position the underside of the lower bolster rests on the upper side of a vertically reciprocable platen 6! whereby the lower mold unit is carried toward and from the upper mold for pressing plastic material between the mold cavities thereof and releasing the pressure on said material after the same has been formed into the desired shape. The raising of the platen is effected by a hydraulic motor which comprises a pressure cylinder 62 arranged vertically in the base of the frame and an elevating ram 63 having its lower part movable vertically in the cylinder 62 and having the platen 6i secured to the upper end thereof by bolts 64, as best shown in Fig. 3. Upon admitting fluid, such as water under pressure, to the cylinder 62 the ram 63 and the parts resting thereon will be raised and upon permitting this pressure fluid to escape from this cylinder the mold elevating ram 63 will be lowered by gravity aided in the present case by a pull back hydraulic motor as will presently appear. In the lowermost position of the elevating ram 63 the lowermold unit inclines forwardly and has its rear part overhanging the front part of the platen, as shown in Fig. 3. In this position of the lower mold unit its rear part is supported by rollers 10 pivotally mounted on opposite sides of the rear part of the lower bolster 54 and resting on the downwardly inclined front surfaces 65 of two tracks or rails BSsecured to the adjacent parts of the inner sides of the frame side plates, as shown in Fig. 3. At this time the outer part of the lower mold unit is supported by two vertically swinging shift levers arranged on opposite sides of the platen and lower mold unit and each of these levers being pivoted between its with the lowerbolster by a pin ll arranged on the rearwardlmthereby causing are in engagement front part of the respective side of the lower bolster and'passing through an upright: slot 12 in the upper arm of this shift lever,as'shown:in Fig. 6. The lower arm 68 of each of the mold shift levers is providedwith a laterally projecting pinlt which engages with a cam slot of sub-' lstantially L-shape formed in a cam plate I l secured to the adjacent side plate of the frame and having an upright dwell portion l5 and a shifting portion 16 'extending rearwardly from the lower end of the dwell portion, as'shown in 6 v v V In the fullylowered position of; the elevating "ram each of the shifting levers is turned so that its inner arm 68 is, moved rearwardly and upwardly and its pin 13 engages with the lower shift- :ing' part '56 of the card slot and theupper arm 6-! of thislever is moved forwardly and downwardly andthe lower end of itsslot l2 isengaged by the adjacent front pin H on the corresponding side of the lower bolster whereby the latter is supported in a downwardly inclined position, as shown in Fig. 3. l

During the first part of the upward movement of the elevating ram 63 the lower arms 68 of the mold shift levers are turned downwardly and forwardly by the action of the lower, shifting parts lii ofthe cam slots in the plates l4 and the upper arms of these levers are moved upwardly and the rear part of the lower mold unit to be lifted by the rollers '56 run 'ning up the inclined surfaces 65 of the rails 6% andthe front part of this. mold unit to be lifted to greater-1 extent by the shift levers, While .thelower mold unit is thus lifted by the rails 66 and the shifting levers 61,68 .itis also moved bodily rearwardly until its rollers Til engage with the horizontal rearmostupper surfaces ll of the ,tracks as at which time the mold unit is arranged horizontally and the platen iii has risen into engagement with the-underside of the lower bolster and the dwell portions 15 of the cam slots with the pin 13 of the shift levers, as shown in Fig, 6.

By'this manner ofmounting the upper and lowermold carying units a considerable tilting action is obtained during a comparatively short longitudinal movement of the same, thereby expediting the operation of the press, minimizing the space required for this operation and enabling a considerable tilting of the upper and lower molds to be obtained while the rear parts of :the' same still overlapthe frame head and platen. f n l During the time that the lower mold unit is moving rearwardly into a horizontal position over the platen, the upper mold unit is simultaneously moved rearwardly into a horizontal position into engagement with the underside of the frame head, this action of the upper mold unit being effected by a shifting mechanism which derives its motion from the elevating ram 53. In its preferred form this shifting mechanism comprises a vertically sliding shifting plate F8 which is guided in vertical ways 19 on therear side of the frame, head, a link 8i) connecting the'lower end of'this' shifting plate with the rear part of the platen 6!, a pair of upright cam levers Bl arranged on oppositesi'des of a lug B2 projecting rearwardly fromjthe' shiftingqplate 18 and pivoted concentrically on a the elevating ram 63 has horizontal pivot pin 83 mounted transversely-on therrear sidebf the frame head, shifting rollers 84 mounted on opposite sides of the lug 82 of the sliding plate 'lii and engaging with cam slots 85 in the cam levers ill, and horizontal links'fi i connecting the lower ends of the cam levers 8| with the rear end of the upper bolster 3 'of the upper mold unit. The timing of the movements of the several parts described is such that when mined distance short of the end of its upward stroke, the upper and lower mold unitswill be parallel and opposed to each other but still sep arated some distance which in the instant case is two and one-half inches. During the final part of the upward or squeeze movement of the elevating ram the upper and lower mold units are in parallelism and the lower mold is pressed toward the upper mold so as to compress the plastic or other material which is contained in the complementary mold cavities thereof and been raised a predetercause the same to conform thereto for completing the shaping of the articles under pressure;

During the last part of the upward movement of'the lifting ram the lower mold unit is subjected to ihigh'pressure and forced toward the them and producing a final heavy squeeze on the material forcompleting the formation of the The'slots "E2 in the upper arms 61' of same: the shifting levers permit a slight, play between the same and the pins ll of the lower bolster in order to compensate for the diiferences in the'direction of movement of these levers and thelower bolster upon'moving the latter inwardly and outwardly relative to the main Centering means are provided for the purpose of compelling the lower and upper moldsto come togethenwith' thelcomplementary mold cavities thereof i'n exact register. Toraccomplish this resu'lt'the-upper-mold is provided on its front and rear sides with downwardly projecting cen ,te ring' dowel pins 3! which enter eyes 88 on the '1 When firstsetting' up the press the complementary cavities of the upper and lower molds may not be in exact register in a direction fore and an the press and for this reason a Vernier or firi'e-adjmtment means are provided to secure accurate longitudinal alinement of the lower 'mold'relative'to the upper. The preferred means for this purpose, best 'shown'in Figs. -1, 8, l0 and 113; are constructed asfollows:-

The numeral 39 represents two adjusting blocks arranged on opposite sides of the front p'artofthe lower bolster 55, each of these blocks carrying one of the shifting pins "l l and guided for horizontalmovement on this bolster by making the same T-shaped in cross section and arranging the head of the T in the rear part of a correspondingly shaped guideway 90 formed lengthwise ,in' the adjacent part of the lower Lbolster 54, as shown'in Fig. 13, thereby prevent ing thisblock and bolster from moving in any direction relativeizo each other excepting in a direction lengthwise of the guideway 93.;

Each of the adjusting blocks. is associated with a longitudinal adjusting screw having a rear threaded shank 9i which works in a threaded upper mold unit for taking out any slack between,

opening in the respective block, a front unthreaded stem. 92 which turns in a thrust block 93 mounted in the front part of the guideway on the adjacent part of the lower bolster 54, a collar or shoulder 94 adapted to engage with the rear side of the thrust block 93, a screw nut 95 working on the threaded front end of the stem 92, and a washer 96 interposed between the rear side of the nut 95 and the front side of a thrust plate 91 secured to the adjacent front part of the lower bolster and engaging with the front side of the thrust block 93. Upon backing the nut 95 away from the washer 96 and turning the adjusting screw so that its collar 94 pushes forwardly on the block 93 then the lower bolster will be moved forwardly relative to the pivot II of the respective shifting lever 67, 68 and upon turning this adjusting screw in the 0pposite direction the nut 95 will press against the front side of the abutment plate 9'! through the medium of the interposed washer 96 and move the lower bolster rearwardly, after which this nut may be again tightened on the stem of this screw for holding the parts in their adjusted relation in which the cavities of both molds are in correct alinement. The turning of this adjusting screw may be effected by applying a wrench to the squared front end 98 of this screw.

Means are provided for firmly holding the upper and lower mold units on the frame head and platen and locking or retaining these parts securely against lateral displacement relative to each other in order to attain the maximum perfection in the articles which are produced. These means, which are best shown in Figs. 3, 6, 7, 11 and 12, are constructed as follows:-

Projecting downwardly from the underside of the frame head 3I adjacent to opposite sides of the upper bolster 31 are front and rear looking or retaining brackets 99 each of which is pro!- vided with an inner vertical longitudinal retaining surface I00, and an upper horizontal retaining surface I M arranged at the lower end of the vertical surface I00 and having a rounded or curved front end I02. On opposite longitudinal sides of the upper bolster the same is provided with front and rear looking or retaining shoes I03 each of which has an outer vertical longitudinal retaining surface I 04, and a lower longitudinal retaining surface I05 which is rounded or curved at its rear end I06. When the upper mold unit is in its foremost position shown in Fig. 3, the retaining shoes of the upper bolster are out of engagement from the upper retaining brackets 99 but during the last part of the rearward movement of the upper mold unit each of the retaining shoes of the upper bolster engages its vertical and horizontal retaining surfaces I04, I05 with the corresponding vertical and horizontal retaining surfaces I00, IOI of the comp-anion bracket 99 on the frame head, thereby locking the upper mold unit securely to the frame head so that the upper mold is held rigidly in place and will not become displaced during the pressing operation. The co -operating horizontal surfaces of the upper retaining brackets and shoes are guided vertically relative to one another by engagement of the rounded ends I02 and I 06 on the upper retaining brackets and shoes.

Projecting upwardly from opposite side of the platen BI are front and rear locking or retaining brackets I08, I 09 each of which is provided with an upright longitudinal inner retaining surface H0 and a lower horizontal longitudinal retaining surface III which extends inwardly from. the upper end of the vertical surface IIO, as best shown in Figs. 11 and 12. Each of the horizontal retaining surfaces is provided with a rounded front end II 2, as shown in Fig. 6. Projecting from opposite sides of the lower bolster 54 are front and rear retaining or looking shoes H3, H4 each of which has a vertical outer longitudinal surface H5 and an upper horizontal longitudinal surface II 6 extending inwardly from the upper end of this vertical surface. When the lower mold unit is in foremost position, as shown in Fig. 3, the looking or retaining shoes of the lower bolster are out of engagement with the lower looking or retaining brackets I08, I 09 of the platen, but during the last part of the backward movement of the lower mold unit the horizontal and vertical faces of the front and rear locking shoes H3, H4 engage the corresponding faces of the front and rear locking brackets, I08, I09, respectively, and thereby rigidly lock the lower mold unit against displacement rela tive to each other during the operation of the press. Vertical guiding of the horizontal co -operating surfaces of the lower locking shoes and brackets is effected by co-operation of rounded surfaces II! on the rear ends of these shoes with the rounded surfaces II 2 at the front ends of the brackets, as shown in Fig. 6.

In the closing operation of the press the platen effects the first part of its rising movement while the lower mold unit is moved rearwardly over the platen. During this operation the rear locking shoes II4 of the lower bolster must first pass the front locking brackets I 08 of the platen and thereafter interlock with the rear brackets I09 of the platen at the same time that the front locking shoes II3 of the lower bolster interlock with the front locking brackets of the platen. To permit of this relative movement of these parts without conflicting with one another, the front brackets I 08 are arranged farther away from the sides of the lower bolster than the rear brackets I09, and the front shoes I I3 are made comparatively wide while the rear shoes II4 are made relatively narrow, as shown in Figs. 11 and 12. By this means the narrow rear shoes II4 are able to first pass rearwardly between the widely spaced front brackets I08 and then interlock with the narrowly spaced rear brackets I 09 at the same time that the wide front shoes II 3 are interlocked with the widely spaced front brackets, and thus avoid interference between any of the moving parts.

Instead of depending solely on tion of the lifting or elevating ram 63 in the cylinder 62 as: part of the means for guiding the platen in its vertical movement, greater accuracy in the control of the platen is obtained by additionally guiding the same by means of vertical runners II 8 arranged on. the corners of the platen and having bevelled faces I I9 which engage with the bevelled faces I 20 of upright guide rails I2I mounted on the adjacent inner parts of the frame sides, as shown in Figs. 1, 8 and 20.

After the platen has completed its upward stroke and the pressing of the materials between the molds has been finished the downward or opening movement of the platen and the parts operatively associated is effected by power which is derived from a hydraulic pull-back motor which is preferably organized as follows:-

The numeral I22 represents two upright hydraulic pull-back rams arranged in front and in rear of the frame base and each passing through the sliding acthe lower endof and movable vertically in a hydraulic pull-back cylinder I23 mounted on the adjacent upper part of the frame base, 'as'best shown in Figs. 1', 3, 6, 8 and 15. The lower end of each pull-back ram is connected with a horizontal transverse cross bar I24 the-opposite ends oflwhichare connected with the lower ends of two p-ull rods E25 arranged vertically on opposite sides: of the respective pull-back cylinder I23. The upper ends of the pull-back rods associated with each pull-back ram are connected with 'a bracket I26 on the adjacent part of the platen and between the upper and lower ends of these rods the same are guided in brackets I21 on the adjacent upper part of the frame base, as shown in Figs. 1, 2 and 6. Upon admittinga pressure medium, such as water under pressure, to the upper ends of the pull-back cylinders the rams therein will be forced downwardly togetherwith the platen connected therewith, and upon discharging this pressure fluid from the pull-back cylinders the rams therein are free to be raised by the upward working stroke of the elevating or lifting ram.

' After the articles have been completely formed bycompression of the material between the mold cavities of the two molds these articles remain in the cavities 36 of the lower mold during the initial part of the downward or opening movement of the latter. Immediately after the platen and the lower mold unit have effected the first part of their downward movement and before this mold unit begins its forward movement and is inclined forwardly, the formedarticles in the cavities of the lower mold are ejected or stripped therefrom to facilitate their removal from this mold preparatory to replacing the finished articles with unfinished material. For thispurpose automatically actuated stripper means are provided which are constructed as follows and best shown in Figs. 3, 8, 9, and 10-22:--- V The numeral I28 represents a plurality of upright stripper pins eachofwhich is movable ver-' tically in a suideway formed partly by anopen- ,ing I29 inthe lower mold and partly by an opening itil'in the upper part of the lower bed plate orfiller plate 29. Each of these stripper pins is arranged in' line with one of the cavities 36 in the lower mold and has its lower end arranged in a lifting chamber I3I formed in the underside of thebed 29. [The upper end'of each stripper pin is adapted to be loweredinto a positionin which it is flush with the bottom of the respective mold cavity 36 when the same is empty and ready to be filled with unfinished material, as shown in Fig. 3, and the upper endof'this pin is also flush with the bottom of the respective mold cavity during the operation of pressing the material so that it conforms to the shape of the respective mold cavity. After the compression of the material into the desired shape between the cavities of the upper and lower molds has been completed and the lower mold has effected the first part of its downward movement the several stripper pins are raised so that the upper end of each of these pins projects above the bot tom of the respective mold cavity, as shown by dotted lines in Fig. 9, thereby lifting or ejecting the molded articles from the lower mold cavities and permitting the same to be readily removed from the lower mold. Simultaneous raising of the several stripper pins is effected by a stripper plate 32 arranged horizontally inrthe lifting chamber i3I below the lower ends of the pins I23 ..When the stripperplateis in its lowermost position it rests on the upper side of the lower bolster 54 which forms the bottom of'the lifting a chamber. I3l, as shown by full lines in Fig. 9,

and upon raising the stripper plate, as shown by dotted lines in the same figure, the same will raise all of the stripper pins and eject the pressed articles from thelowerrnost cavities 36. The numeral I33 represents a plurality of stripper locking pins, preferably four in number slidable Ver tically in guide openings I34 formed in the lower bolster 54 adjacent to the corners thereof and underneath the stripper plate I32. When these locking pins are in-their lowermost position the upper ends of the same are preferably flush with the top the lower bolster and their downward movement is limited by a stop shoulder I35 arranged on the upper partof each locking pin and engaging a corresponding stop shoulder I36 in the bore of the respective guide opening I34,.as shown in Figs. 9 and 22. 0n the lower part of each locking pin I33 the same is'provided' with a reduced part I31 forming a downwardly fac ing shoulder I33 thereon between this lower reduced part and the upper larger part ofthis pin. Upon pushing. the locking pins upwardly, the same raise the stripper plate I32 and the latter in turn raise the stripper pins for ejectingthe pressed articles. Looking means are provided for automatically holding the locking pins in an elevated position after the same have been raised and manually releasing the same so as to again permit their descent. These locking means include two longitudinally movable locking bars I39 guided in longitudinalhorizontal guideways I40 on the lower bolster adjacent to opposite sides of the same. Eachof these locking bars is provided with two key-hole openings which receive the lower parts. of two of the locking pins, each of these openings having a widerear part MI and a narrow front part I42, as best shown in Fig. 14.

In the lowered position of thelocking pins the large part of each pin engages with the large part I4I of one of the locking openings in one of the locking bars and each of the latter presses the front sides of the large parts of said openings against the front sides of the large parts of said locking pins by means of a'tensiorr device con-- sisting of a tension rod I43 projecting rearwardly from each locking bar and a spring I44 surrounding each tension rod and bearing at its front end against an abutment plate I45 on the rear .side of thelower bolster while its rear end bears against-a collar I46 on the rear end of said rod, as best shown in Figs. 9 arid 10. The instant the locking pins are raised to a position in which their locking shoulders I38 are above the locking bars I39 then the latterare moved rearward quickly by the springs I44 so as to en-: gage the narrow front part I42 of each locking opening in. these bars with the small lower part I31 of the respective'locking pin so that the lock* ing shoulder I38 of each of these. pins overhangs the adjacent upper sideof the respective locking bar and engages therewith, thereby holding each locking pin in its elevated position, as shown in Fig. 22, together with the parts supported thereon.. When'it' is desired to release the locking pins and permit the same to descendtogether with the parts supported thereby this may be accomplished manually in various ways for example by the means which are shown in Figs. 1, 3, 8, 9 and 10, and which comprise a horizontal rock shaft I41 journaledtransvers'ely in bearings on the front part lot the lower bolster and provided centrally with an. upwardly projecting operating handle I48, and two rock arms I49 projecting upwardly from opposite ends of the rock shaft and each provided with a slot I59 which receives a transverse pin I5I on the front end of one of the locking bars. Upon moving the handle forwardly by hand the shaft I41 and its arms will be turned in direction for moving the locking bars forwardly and disengaging the narrow parts I42 of the key-hole openings from the small parts of the locking pins and also moving forwardly the upwardly facing surfaces of these bars around the narrow parts of these key-hole openings from underneath the locking shoulders I38 of the locking pins whereby the latter are permitted to descend by passing with their large upper parts I33 through the wide rear parts I4I of the key-hole openings as shown in Figs. 9 and 14.

The numeral I52 represents a plurality of upright trip pins which are guided for vertical movement in guideways I53 on the platen and each of which has its upper end arranged below the lower end of one of the locking pins and is yieldingly held in a depressed position by a spring I54 surrounding this pin and bearing at its upper and lower ends against a shoulder I55 on the upper part of the platen and. a shoulder I56 on the intermediate part of this pin, as shown in Fig. 9. The lower ends of the several trip pins engage with the upper side of a trip or releasing ring I5! at different points circumferentially thereof. This trip ring surrounds the upper reduced cylindrical part I 58 of the hydraulic elevating ram 63 and is capable of reciprocating vertical thereon and also oscillating horizontal relatively thereto about the axis of the elevating ram. Downward movement of the trip ring is limited by engagement of its underside with an annular upwardly facing shoulder I59 formed on the exterior of the elevating ram at the lower end of its reduced part I58, as shown in Figs. 3 and 5.

At equidistant points about the periphery of the trip ring the latter is provided with laterally projecting abutment lugs I60, preferably four in number each of which has a solid part I6I and a perforation I62 on one side of the solid part, as shown in Figs. 15, 16 and 17. The numeral I63 represents a plurality of upright thrust rods arranged in a circumferential row around the elevating ram and each mounted at its lower end on the upper part of the frame base so that it is stationary while the upper end of this rod terminates adajacent to one of the thrust lugs I60 of the trip ring.

When the press is closed and the lower mold unit is in its highest position the trip ring I51 is elevated and also turned so that the solid parts I 6| of its thrust lugs engage with the upper ends of the thrust rods I63, as shown in Fig. 16 and at the same time each locking pin I33 and its companion trip pin I52 form a column which is interposed between the underside of the stripping plate I32 and the upper side of the trip ring, which column however has a slight gap between the lower end of the respective locking pin. I33 and the upper end of the trip pin associated therewith, as shown in Fig. 9.

During the initial part of the downward movement of the lower mold unit the slack between the downwardly moving stripper pins I28 and the relatively stationary trip pins I 52 is taken up and immediately following this initial downward movement of the lower mold unit the stripper pins are held against downward movement due to the stripper plate, locking pins, trip pins, trip ring and thrust rods forming a solid support for' the stripper pins on the stationary press frame. The mold unit now continues its downward movement independently of the stripper pins whereby the latter are pushed upwardly into the cavities 36 of the lower mold and dislodge therefrom the molded articles contained therein preparatory to being completely removed by the attendant either by hand, a rake or other tool best suited for this purpose.

Immediately after the finished articles are discharged from the cavities of the lower mold and while the latter in its descent is still in a horizontal position the trip pins I52 are quickly permitted to descend so that their upper ends do not project above the platen and therefore can not interfere with the free forward movement of the lower mold unit for unlocking the same from the platen and the downward tilting of this unit to facilitate the removal of the finished articles from the lower mold and the introduction of new unformed material.

This quick withdrawal of the trip pins from the locking pins is effected by suddenly turning the trip ring about the axis of the elevating ram immediately after the ejecting operation of the stripper pins so that the clearance holes I62 of the thrust lugs I60 are in line with the stationary thrust rod I 63 and when this occurs the trip ring drops by gravity with its clearance or release openings I62 sliding downwardly over the thrust rods I63, as shown in Fig. 17, thereby permitting the trip pins to be withdrawn from engagement with the locking pins before the lower mold unit begins its forward movement. The downward movement of the trip ring on the elevating ram is limited by engagement of this ring with the stop shoulder I59 on this rim. In order to prevent undue noise and wear on the parts when the trip ring drops cushioning means are provided to absorb the shock, which means preferably comprise a plurality of cushioning pins I64 arranged vertically in pockets I65 at different points in the trip ring and each yieldingly held in a position in which the same normally projects with its lower end below the trip ring. For this purpose a spring I66 in each pocket I65 presses downwardly on the cushioning pin therein and the downward movement of the cushioning pin in this pocket is limited by co-operating shoulders I61, I68 formed on this pin and the inside of this pocket, as shown in Fig. 5. When the trip ring'descends the cushioning pins engage the shoulder I59 of the elevating ram first and this absorbs the shock and minimizes noise and wear.

After the lower molding unit has reached its lowermost position in which it inclines forwardly from the platen the operator removes the finished articles and pulls on the handle I48 so as to release the locking bars I39 from the locking pins and permit the stripper pins and stripper plate to drop into their inoperative position. Means are provided for automatically turning the trip ring in one direction for disengaging the trip pins from the locking pins before the lower mold unit begins its forward movement relative to the platen which also turns the trip ring in the opposite direction when the latter is elevated above the thrust rod for bringing the solid parts I6I of this ring over the thrust rod and holding this ring temporarily against downward movement for the purpose hereinbefore described. The preferred means for accomplishing this result are shown inFigs. 1, 2, 6, 8, 15-21 and are constructed as follows:-

The' numeral 204 represents a rocking shift lever which moves bodily up and down with the platen and also turns horizontally relative thereto this being accomplished by pivoting this lever on the adjacent pull rod I25 connected with the rear side of the platen. On its front arm the rock lever 204 is provided with a vertical coupling pin 205 which slidingly engages an opening formed in a part of the trip ring I51, I 86 as shown in Figs. 15, 16 and 17. This shift lever is rocked by actuating means which are mounted on brackets 201, 208 on the rear part of the platen so as to move vertically with the latter which actuating means include a pneumatic motor having a horizontal air cylinder I69 mounted on the bracket 201 and a piston I sliding in this cylinder and having its piston rod I1I connected by a link I12 with the outer arm of the shift lever 204. Air under pressure is admitted to the outer also turns the trip ring I51 endof the cylinder I69 for turning the shift lever 264 in the direction which will turn the trip ring I51 so that each of its solid parts I6I is arranged over the upper end of one of the thrust pins I63 as shown by full lines in Figs. and 16 thereby preventing the trip ring from dropping. Upon exhausting the air pressure from the outer end of the cylinderthis lever 204 will be turned in the opposite direction by spring. return means so that the trip ring I51 will be turned in the opposite direction and bringeach of each release openings I62 over one of the thrust pins I63 and thereby permit the thrust ring to drop for the purpose previously explained.

- These spring return means, as shown in Fig. 15 comprise a push rod I13 connected at one end with the outer arm of the shift lever 204 and passing through a guide eye I14 on the bracket 208, and a spring I15 surrounding this rodand bearing at one end against this guide eye and at its opposite end against a shoulder I16, which is formed by a screw nut on said rod. The instant the'air pressure in the outer end of the cylinder I69 is released, the resilience of the spring I15 moves 'thepiston I10 backwardly and so that its holes I62 are in alinement with the thrust rods I63 and therefore permit this ring to drop and the stripper pins to retract into their depressed inoperative position relative to the cavities in the lower mold, For the purpose of avoiding undue noise, wear and jarring of the press during the sudden return'ac tion of the trip ring under the pressure of the spring I15 cushioning means are provided consisting preferably of acushion spring I11 surrounding the returnrod I13 and bearing at its outer end againstian abutment I18 on this rod while its inner end isadapted to engage with the outer side of the guide eye I14, as shown in Fig. 15.

Compressed air for operating the piston I10 is supplied by a pipe or tube I19 from any suitable source to the front or outer end of the cylinder and the admission of this compressed air to this cylinder and the discharge of the spent air there- 'from is controlled by a valve mechanism which operates automatically inharmony with the movements of the press platen. A satisfactory form of air controlling valve mechanism for this purpose is'shown in Figs. 1,2, 6, 8, 16, 18, 19, 20 and 21, and is constructed as follows:-

The compressed air supply conduit preferably consists of a stationary section mounted on one of the framesides 32 and a'flexible section I60 in order topermit the air cylinder I 69 to rise and fall with the platen. The fixed part I19 of the air supply pipe includes a valve device where by compressed air may either besupplied tothe cylinder I69 or this air supply may be shut off and this cylinder vented to the atmosphere topermit the spent air to escape. This valve device comprises a tubular body I8I connected atits opposite ends with sections of the pipe I19 and provided with a partition I82 and upper inlet ports I83 and lower outlet ports I84 arranged above and below said partition, and a sleeve I65 slidable lengthwise on the exterior side of the valve body and having an interior cavity I86.

Upon moving this sleeve into its lowermost position its cavity I86 will place the upper and lower I84 in communication as shown in ports I83, Fig. 19 and permit compressed air to pass to the front endof the cylinder I69 for moving the solid parts I6| of the trip ring over the thrust rods I63, and upon moving this valve sleeve downwardly into its uppermost position, as shown in Fig. 18, the lower outlet ports I84 will be cut off'from the compressed inlet ports I83 and connected with the atmosphere so that the spent air can escape from the cylinder I69 and'permit the spring I15 to turn the'trip' ring I51 into a position which will permit the stripper pins to drop. The shifting of the air control valve sleeve I86 from one extreme position to the other is effected quickly by a trip device which is actuated by motion derived from the vertically reciprocating platen, this trip device being constructed as follows and best shown in Figs. 18-21:-

The numeral I81 represents a vertically swing,- 4

ing tappet or trip lever pivoted on a pin I88 carried by a stationary bracket I89 on the air supply pipe I19 having its outer arm connected with the valve sleeve I86 and its inner arm provided with upper and lower trip rollers I90, I9I which are arranged above and below, respectively, of the axis of the pivot pin I88; On the adjacent part of the platen two cam shaped tappets I92, I93, are mounted to move vertically therewith, the upper tappet I92 being adapted to engage the lower trip roller I9I and the lower tappet 193 being adapted to engage theupper trip roller I90. .'The lower tappet I93 is preferably fixed on the platen 6| but the upper tappet I92" is made adjustable thereon to suit the character of the molds which are used and the articles to be formed and this adjustment is preferably effected by means of clamping bolts 291 mounted on the platen and passing through a vertical slot 293 in the upper tappet, as shown in Figs. 18, 19 and 21.

During the downward movement of the platen 6| the lower tappet I93 engages the upper roller I90 and turns the tappet lever I81 in the direction for operating the valve sleeve I86 so as to supply air to the shift cylinder I69, as shown in Fig. 19, and during the upward movement of the platen the upper tappet I92 by engaging the 7 lower tappet roller I9I turns the tappet lever I81 in the direction for shifting the valve sleeve I86 so the same cuts off the compressed air supply to the cylinder I69 and vents the latter to the atmosphere for permitting the spring I15 to turn the ring I51 into a position in which the openings'l62 are in alinement with the thrust rods I63 and thus permit the stripper pins to retract from the lower mold cavities during the descent of the lower mold. This air valve trip mechanism is so organized that the air pressure is on the piston I10 during the latter part of the upward stroke of the platen and also the initial downward stroke of the same until the elevating ram has nearly reached that position in its descent when the upper and lower molds begin their forwardly tilting movement. The upward movement of the trip ring E51 is effected by engagement of the shoulder I59 of the elevating ram with this ring as this ram rises and during the greater part of the upward movement of the elevating ram the trip ring slides with its holes I62 upwardly on the thrust rods I 53. When however the trip ring has been raised above the upper ends of the thrust rod then the trip ring is released and quickly turned by the air pressure against the piston I19 for bringing its solid parts IBI over the thrust rods.

After the trip ring has been carried above the thrust rods and has been turned over the same the trip ring continues its upward movement with the platen to complete the closure of the press but after the platen has effected the initial part of its downward movement the trip ring is held against downward movement for a time by the thrust rods so that the stripper pins will discharge the articles in the lower mold cavities. The coupling pin I65 is made sufficiently long to permit this independent movement of the platen which carries the shift lever 264 and the trip ring I51 which has a limited sliding movement on the elevating ram, as shown in Figs. 16 and 17.

In order to cause the trip lever I89 to be moved quickly in both directions, accelerating means are employed which preferably consists of a V- shaped snap cam I94 arranged on the bracket I89 and a plunger I 95 slidable lengthwise in a pocket I96 on the trip lever I81 and held yieldingly in engagement with this snap cam by a spring I91 arranged in the pocket I96 and bearing against said plunger. During the upward movement of the platen the same turns the valve trip lever I81 from the position shown in Fig. 18 to the position shown in Fig. 19 and during the first part of this movement of the platen the lower tappet I93, by engaging the upper tappet roller I90, first turns the tappet lever I81 slowly in an anti-clockwise direction. As the plunger I 95 approaches the high or salient part of the snap cam I94 the tension on the spring I91 is increased so that when the plunger passes over the highest part of this cam the opposite inclined surface of the latter by reaction thereon of the spring pressed plunger I95, will cause the throw of the trip lever I91 in the direction of the arrow to be completed, as shown in Fig. 19, with a quick action. Turning of the tappet lever from the position shown in Fig. 19 to that shown in Fig. 18 is effected in the same manner as the upper tappet I92 by engaging the lower tappet roller I9I so that it first turns the tappet lever I81 slowly in a clockwise direction and causes the plunger I95, by riding toward the high part of the snap cam from right to left, to press back the plunger and increase the tension on the spring I91, and when the plunger has passed the high part of this cam the reaction of the spring pressed plunger against the left hand incline of this cam causes the turning of this lever in a clockwise direction to be completed quickly. I v

The cylinders of the pull-back rams are constantly under high pressure so that they will descend promptly when the upward pressure on the elevating ram is out off, but when high pressure is applied to the elevating ram the larger area of the same causes it to rise and owing to its preponderance over the area of the pull-back rams will prevent any retarding effect by the latter. ,In the operation of the press the first part of the upward movement of the elevating ram is effected comparatively fast and at a relatively low pressure but the final part of this upward movement is effected slowly and under a heavy pressure, so as to properly form the articles between the molds.

Each of the locking pins I33 and its companion shifting pin I52 in effect form the upper and lower sections of a shifting member for transmitting the action of the trip or ejecting ring I51 to the stripper pins but division of each of these shifting members into sections as shown is necessary in order to permit that part of the stripper mechanism on the lower mold unit to move forward off the platen while the latter remains behind on the lifting ram.

By employing a spring I 15 to move the trip ring I51 in a direction opposite to the effect on this ring of the pneumatic motor piston I1I, safety against injuring the press is assured in the event that the molds are operated when the compressed air for the pneumatic motor fails, because the spring I15 under such circumstances would hold the trip ring I51 in a position to present its clearance holes I62 over thrust pins I63 and thus permit this ring to descend with the platen, otherwise the intermediate shifting pins I52 would be left in a position in which the same project above the platen and therefore would be sheared off by the bolster of the lower mold unit as the latter moves forwardly off the platen and into an inclined position for discharging the fi'nished product and taking on new material.

Any suitable valve mechanism may be employed for controlling the action of the pressure fluid on the mold lifting ram 53 and the pullback rams I22, that shown generally at 399 in Fig. 1 being organized to maintain a high pressure on the pull-back rams at all times, a low pressure on the mold lifting ram during the main part of the upward movement of the latter for rapidly closing the molds and a high pressure on the lifting ram for the purpose of producing a final heavy squeeze on the material between the molds and producing finished articles therefrom. Although the pressure is on the pull-back rams at the same time that it is on the lifting rams, the latter nevertheless are ineffective during the up ward movement of the lifting ram and rise with the latter because the area of the lifting ram is considerably greater than that of the pull-back rams, but when the pressure is cut off from the lifting ram the constant pressure on the pullback rams causes the latter to be immediately lowered and the press to be opened.

We claim as our invention:-

1. A molding press comprising a frame, upper and lower cooperating mold units arranged with-- in said frame, means for moving said upper unit into an operative position parallel with the lower unit and into a laterally inclined inoperative position including downwardly curved tracks arranged on the frame, and supporting members arranged on the uppermold unit and running on said tracks, and means for moving said lower mold unit toward andfrom the upper mold unit including a shifting lever pivoted on the frame and connected with said upper unit and provided with a cam slot, and a vertically movable slide having a pin working in said cam slot.

2. A molding press comprising a frame, upper and lower cooperating mold units arranged within said frame, means for moving said upper unit into an operative position parallel with the lower aoezgeeo meansrfor interlocking the upper mold-unit with 7 said frame-in its operative position. Y

3. Aimolding; press comprising a frame, upper andlower cooperating mold units arranged within: said frame, means for moving-said upper unit into an operative position parallel with theslower brackets mounted on the an operative 1 ranged on the front unit and into'a laterally inclined'inoperative position including downwardlycurved tracks arranged on the frame, and supporting members arranged on the upper mold unit and running on said tracks, means for moving said lower mold unit toward andfrom the upper mold unit, and means for interlocking the upper moldunit with said frame in its operative position, including brackets arrangedon the frame andhaving ver tical and horizontal guiding surfaces, and shoes mounted on the upper mold unit and having vertical and horizontal guiding surfaces adapted to engage with corresponding surfaces of said brackets.

4. A molding press comprising a frame, upper and lower cooperating mold units, means for moving said upper unit into a horizontally operative position and also into an inclinedinoperative position relative to said frame, including upper tracks mounted on the frame and supporting members on the uppermold' unit running on'said upper tracks, means for moving said lower unit in position toward 1 and. from the upper unit and also into a laterally inclined inoperative position including lower tracks mounted on the frame, lower. supporting members on a the lower unit running on said lower tracks, a vertically movable platen carrying said lower mold unit, means for interlockingsaid upper mold unit with the frame including upper. front and rear front and rear parts of said frame and upper front and rear shoes arand rear parts of the upper mold unit and adapted to interlock. with said front and rear brackets, respectively; and means for interlocking the lower mold unit with the platen including lower front and: rear brackets arranged on the front and rear parts of the platen, and lower front and rear shoes arranged on the front and rear parts of the lower mold unit and adapted to interlock with the lower front. and rear brackets, respectively, the companion front brackets and shoes between the front parts of the mold units and the frame and platen-being spaced farther apart than the companion brackets and shoes between the rear parts of the mold units and the frame and platen.

5. A molding press including a molding unit having a mold cavity, a stripper pin movably mounted on said mold unit and adapted to eject the article from said cavity after the same has been formed therein, and locking means for holding said pin in its projected position relative to said mold cavity, said locking meansincluding a locking pin guided on the mold unit and adapted to lift said stripper pin, means for lifting said locking pin, and a locking device on said mold unit for holding said locking pin in its elevated position.

6.,A, molding press. including a molding unit having a: mold cavity,.a stripper pin movably mounted on said mold unit and adapted to eject the article from said cavit after the samehasbeen formed therein, and lockingmeans forholdingsaid pin in its projectedposition' relative to said mold cavity, said locking means including alocking pin guided on themold unit and adapted to lift said stripper pin and having a locking shoulder, means for lifting said locking pin, and a locking bar slidable on said mold unit' and having alocking shoulder-adapted to be engaged with the shoulder of said lockingpin for holdingthe latter in its elevate-d'position and to be disengaged from the shoulder of said locking pin to permit the latter to descend.

7. A molding press including a molding unit having a mold cavity, a stripper pin movably mounted on-said-mold unit andadapted to ejectthe article from said cavityafter the same has been formed therein, and locking means for-holding said pin in. its projected position relative to said mold cavity, said locking meansincluding a locking pin guided on the mold unit and adapt-= ed to lift said stripper pin and having a locking shoulder, means for liftingsaid locking pin, a locking bar slidable on said mold unit and having a locking shoulder adapted to be engaged with the shoulder of said locking pin for holding the latter in its elevatedposition and to be disengaged from the shoulder of said-locking pin to permit the latter to descend, springmeans for moving saidlocking bar in the. direction for looking said locking pin in an elevated position, and

manually operated means for movingthe locking bar in the direction forreleasing said locking-pin and permitting the same to descend.

8. A molding presscomprisingupper and lower mold units providedintheir opposing faces" with cooperating mold forms, meansfor moving the lower mold unit toward and from the upper mold unit'including a vertically movable platen upon which said lower mold unitis mounted, stripper pins movably mounted on the lower mold unit and adapted to engage the articles-from the forms of said lower mold unit, locking meansfor holding said stripper pins in an elevated position, and thrust means which are relativelystationary andwhich during the downwardmovement of said platen and-lowermold unit operate to project the stripper pins into the forms of said=lower mold unit andeject the articles from the forms thereon,

9. A molding press comprisingupper and lower mold units provided in'theiropposing faces with cooperating mold forms, means, for moving the lower mold unit toward and from the upper mold unit including a vertically movable'platen upon which said lower mold unit is mounted, stripper pins movably mounted on the lower mold-unit and adapted to engage the articles fromthe forms of said lower moldunit, locking means for holding said stripper-pins in an elevated position,and thrust means which are relatively stationary and which during the downward movement of said platen and lower mold unit operate to project. the stripper pins into-the forms of said lower mold unit and eject the articles from the forms thereon,

said thrust means including shifting pins guided for vertical movement on said platen-and engaging the lower ends of said locking pins, stationary upright thrust members, and an intermediate releasing member engaging with the lower ends of saidshifting pinsand movable vertically. for liftingtheshifting pins and also movable horizontally for bringing the releasing member over said thrust members and movement or clearing said thrust members and permitting said releasing member to descend.

10. A molding press comprising a frame, an uparresting its downward per mold unit adapted to be supported stationarily on the upper part of said frame, a lower mold unit movable toward and from the upper mold unit, a vertically movable platen on which said lower mold unit is mounted, a hydraulic motor having a vertically movable ram which carries said platen and which has an upwardly facing shoulder, stripper pins movable vertically on said lower mold unit and adapted to eject the formed articles from the lower mold unit, shifting pins slidable vertically on said platen and operating on said stripper pins to lift the same, stationary thrust pins arranged around said ram below said shifting pins, and a trip ring surrounding said ram andadapted to be engaged by the shoulder thereof for raising said ring and the latter engaging with the lower end of said shifting pins, and operating means for turning said trip ring either into a position in which the same engages its underside with the upper ends of said thrust pins or into a position in which said trip ring clears said thrust pins.

11. A molding press comprising a frame, an upper mold unit adapted to be supported stationarily on the upper part of said frame, a lower mold unit movable toward and from the upper mold unit, avertically movable platen on which said lower mold unit is mounted, a hydraulic motor having a vertically movable ram which carries said platen and which has an upwardly facing shoulder, stripper pins movable vertically on said lower mold unit and adapted toeject the formed articles from the lower mold unit, shifting pins slidable vertically onsaid platen and operating on said stripper pins to lift the-same, stationary thrust pins arranged around said ram below said shifting pins, a trip ring surrounding said ram and adapted to be engaged by the shoulder thereof for raising said ring and the latter engaging with the lower endof said shifting pins, operating means for turning said trip ring either into a. position in which the same engages its underside with the upper ends of said thrust pins or into a position in which said trip ring clears said thrust pins, actuating means for oscillating said trip ring including a pneumatic motor for holding said trip ring over said stationary thrust pins during the initial part of the downward movement of the ram, and spring means for turning said trip ring from over said thrust pins after the ram has effected the initial part of its downward movement.

12. A molding press comprising a frame, an upper mold unit adapted to be supported stationarily on the upper part of said frame, a lower mold unit movable toward and from the upper mold unit, a vertically movable platen on which said lower mold unit is mounted, a hydraulic motor having a vertically movable ram which carries said platen and which has an upwardly facing shoulder, stripper pins movable vertically on said lower mold unit and adaptedto eject the formed articles from the lower mold unit, shifting pins slidable vertically on said platen and operating on said stripper pins to lift the same, stationary thrust pins arranged around said ram below said shifting pins, a trip ring surrounding said ram and adapted to be engaged by the shoulder thereof for raising said ring and the latter engaging with the lower end of said shifting pins, and operating means for turning said trip ring either into a position in which the same engages its underside with theupper ends of said thrust pins or into a position in which said trip ring clears said thrust pins/actuating means for oscillating said trip ring including a pneumatic motor, a rock lever connecting said motor with said ring, and spring means connected with said lever, said motor adapted to move said ring over said stationary thrust pins, and said spring means adapted to move said ring away from said thrust pins.

13. A molding press comprising a frame, an upper mold unit adapted to be supported stationarily on the upper part of said frame, a lower mold unit movable toward and from the upper mold unit, a vertically movable platen on which said lower mold unit is mounted, a hydraulic motor having a vertically movable ram which carries said platen and which has an upwardly facing shoulder, stripper pins movable vertically on said lower mold unit and adapted to eject the formed articles from the lower mold unit, shifting pins slidable vertically on said platen and operating on the said stripper pins to lift the same, stationary thrust pins arranged around said ram below said shifting pins, a trip ring surrounding said ram and adapted to be engaged by the shoulder thereof for raising said ring and the latter engaging with the lower end of said shifting pins, operating means for turning said trip ring either into a position in which the same engages its underside with the upper ends of said thrust pins or into a position in which said trip ring clears said thrust pins, actuating means for oscillating said trip ring including a pneumatic motor for holding said trip ring over said stationary thrust pins during the initial. part of the downward movement of the ram, spring means i for turning said trip ring from over said thrust pins after the ram has effected the initial part of its downward movement, a conduit for supplying compressed air to said pneumatic motor and containing a valve having a movable valve memher for connecting said conduit with or disconnecting the same from said motor and connecting this motor with the atmosphere, and a tappet mechanism whereby said valve is operated during the upward movement of said ram for cutting off #1..

the air supply to said pneumatic motor and during the downward movement of said ram admitting the air to said pneumatic motor.

14. A molding press comprising a frame having an upper head and a lower base, a hydraulic motor having a cylinder arranged in the base and a ram movable vertically in the cylinder, a vertically movable platen mounted on 'the ram, an upper mold unit adapted to be held stationary on the frame head and to be moved laterally therefrom into and out of an inclined position relative thereto, a lower mold unit adapted to be held on said platen in a position parallel with the upper mold unit and to be moved laterally therefrom into and out of an inclined position relative thereto, means for stripping the articles from the lower mold unit after being formed between the mold units including stripper pins mounted on the lower mold unit, and means for actuating said stripper pins including parts i:

mounted on said lower mold unit and parts mounted on said platen, said parts being adapted to cooperate while the mold units are parallel and to be disengaged from one another when the lower mold unit is inclined to the platen.

I-IARDIN D. THWEATT. OTTO HOFFMANN. 

